1 /*

     2  * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #ifndef SHARE_VM_RUNTIME_SAFEPOINTMECHANISM_HPP

    26 #define SHARE_VM_RUNTIME_SAFEPOINTMECHANISM_HPP

    27 

    28 #include "runtime/globals.hpp"

    29 #include "utilities/globalDefinitions.hpp"

    30 #include "utilities/macros.hpp"

    31 #include "utilities/sizes.hpp"

    32 

    33 // This is the abstracted interface for the safepoint implementation

    34 class SafepointMechanism : public AllStatic {

    35   enum PollingType {

    36     _global_page_poll,

    37     _thread_local_poll

    38   };

    39   static PollingType _polling_type;

    40   static void* _poll_armed_value;

    41   static void* _poll_disarmed_value;

    42   static void set_uses_thread_local_poll()            { _polling_type     = _thread_local_poll; }

    43 

    44   static void* poll_armed_value()                     { return _poll_armed_value; }

    45   static void* poll_disarmed_value()                  { return _poll_disarmed_value; }

    46 

    47   static inline bool local_poll_armed(JavaThread* thread);

    48 

    49   static inline bool local_poll(Thread* thread);

    50   static inline bool global_poll();

    51 

    52   static inline void block_if_requested_local_poll(JavaThread *thread);

    53 

    54   static void default_initialize();

    55   static void initialize_serialize_page();

    56 

    57   static void pd_initialize() NOT_AIX({ default_initialize(); });

    58 

    59   // By adding 8 to the base address of the protected polling page we can differentiate

    60   // between the armed and disarmed value by masking out this bit.

    61   const static intptr_t _poll_bit = 8;

    62 public:

    63   static intptr_t poll_bit() { return _poll_bit; }

    64 

    65   static bool uses_global_page_poll() { return _polling_type == _global_page_poll; }

    66   static bool uses_thread_local_poll() { return _polling_type == _thread_local_poll; }

    67 

    68   static bool supports_thread_local_poll() {

    69 #ifdef THREAD_LOCAL_POLL

    70     return true;

    71 #else

    72     return false;

    73 #endif

    74   }

    75 

    76   // Call this method to see if this thread has depending poll and appropriate action should be taken

    77   static inline bool poll(Thread* thread);

    78 

    79   // Blocks a thread until safepoint is completed

    80   static inline void block_if_requested(JavaThread* thread);

    81 

    82   static inline void arm_local_poll(JavaThread* thread);

    83   static inline void disarm_local_poll(JavaThread* thread);

    84 

    85   // Setup the selected safepoint mechanism

    86   static void initialize();

    87   static void initialize_header(JavaThread* thread);

    88 };

    89 

    90 #endif // SHARE_VM_RUNTIME_SAFEPOINTMECHANISM_HPP